ns_parse.c

   1 /*
   2  * Copyright (c) 1996,1999 by Internet Software Consortium.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
   9  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  11  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  13  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  14  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  15  * SOFTWARE.
  16  */
  17
  18 #ifndef __APPLE__
  19 #ifndef lint
  20 static const char rcsid[] = "$Id: ns_parse.c,v 1.1 2006/03/01 19:01:37 majka Exp $";
  21 #endif
  22 #endif
  23
  24 /* Import. */
  25
  26 #ifndef __APPLE__
  27 #include "port_before.h"
  28 #endif
  29
  30 #include <sys/types.h>
  31
  32 #include <netinet/in.h>
  33 #include <arpa/nameser.h>
  34
  35 #include <errno.h>
  36 #include <resolv.h>
  37 #include <string.h>
  38
  39 #ifndef __APPLE__
  40 #include "port_after.h"
  41 #endif
  42
  43 /* Forward. */
  44
  45 static void     setsection(ns_msg *msg, ns_sect sect);
  46
  47 /* Macros. */
  48
  49 #define RETERR(err) do { errno = (err); return (-1); } while (0)
  50
  51 /* Public. */
  52
  53 /* These need to be in the same order as the nres.h:ns_flag enum. */
  54 struct _ns_flagdata _ns_flagdata[16] = {
  55         { 0x8000, 15 },         /* qr. */
  56         { 0x7800, 11 },         /* opcode. */
  57         { 0x0400, 10 },         /* aa. */
  58         { 0x0200, 9 },          /* tc. */
  59         { 0x0100, 8 },          /* rd. */
  60         { 0x0080, 7 },          /* ra. */
  61         { 0x0040, 6 },          /* z. */
  62         { 0x0020, 5 },          /* ad. */
  63         { 0x0010, 4 },          /* cd. */
  64         { 0x000f, 0 },          /* rcode. */
  65         { 0x0000, 0 },          /* expansion (1/6). */
  66         { 0x0000, 0 },          /* expansion (2/6). */
  67         { 0x0000, 0 },          /* expansion (3/6). */
  68         { 0x0000, 0 },          /* expansion (4/6). */
  69         { 0x0000, 0 },          /* expansion (5/6). */
  70         { 0x0000, 0 },          /* expansion (6/6). */
  71 };
  72
  73 int ns_msg_getflag(ns_msg handle, int flag) {
  74         return(((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
  75 }
  76
  77 int
  78 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
  79         const u_char *optr = ptr;
  80
  81         for ((void)NULL; count > 0; count--) {
  82                 int b, rdlength;
  83
  84                 b = dn_skipname(ptr, eom);
  85                 if (b < 0)
  86                         RETERR(EMSGSIZE);
  87                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  88                 if (section != ns_s_qd) {
  89                         if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
  90                                 RETERR(EMSGSIZE);
  91                         ptr += NS_INT32SZ/*TTL*/;
  92                         NS_GET16(rdlength, ptr);
  93                         ptr += rdlength/*RData*/;
  94                 }
  95         }
  96         if (ptr > eom)
  97                 RETERR(EMSGSIZE);
  98         return (ptr - optr);
  99 }
 100
 101 int
 102 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
 103         const u_char *eom = msg + msglen;
 104         int i;
 105
 106         memset(handle, 0x5e, sizeof *handle);
 107         handle->_msg = msg;
 108         handle->_eom = eom;
 109         if (msg + NS_INT16SZ > eom)
 110                 RETERR(EMSGSIZE);
 111         NS_GET16(handle->_id, msg);
 112         if (msg + NS_INT16SZ > eom)
 113                 RETERR(EMSGSIZE);
 114         NS_GET16(handle->_flags, msg);
 115         for (i = 0; i < ns_s_max; i++) {
 116                 if (msg + NS_INT16SZ > eom)
 117                         RETERR(EMSGSIZE);
 118                 NS_GET16(handle->_counts[i], msg);
 119         }
 120         for (i = 0; i < ns_s_max; i++)
 121                 if (handle->_counts[i] == 0)
 122                         handle->_sections[i] = NULL;
 123                 else {
 124                         int b = ns_skiprr(msg, eom, (ns_sect)i,
 125                                           handle->_counts[i]);
 126
 127                         if (b < 0)
 128                                 return (-1);
 129                         handle->_sections[i] = msg;
 130                         msg += b;
 131                 }
 132         if (msg != eom)
 133                 RETERR(EMSGSIZE);
 134         setsection(handle, ns_s_max);
 135         return (0);
 136 }
 137
 138 int
 139 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 140         int b;
 141
 142         /* Make section right. */
 143         if (section >= ns_s_max)
 144                 RETERR(ENODEV);
 145         if (section != handle->_sect)
 146                 setsection(handle, section);
 147
 148         /* Make rrnum right. */
 149         if (rrnum == -1)
 150                 rrnum = handle->_rrnum;
 151         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 152                 RETERR(ENODEV);
 153         if (rrnum < handle->_rrnum)
 154                 setsection(handle, section);
 155         if (rrnum > handle->_rrnum) {
 156                 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
 157                               rrnum - handle->_rrnum);
 158
 159                 if (b < 0)
 160                         return (-1);
 161                 handle->_msg_ptr += b;
 162                 handle->_rrnum = rrnum;
 163         }
 164
 165         /* Do the parse. */
 166         b = dn_expand(handle->_msg, handle->_eom,
 167                       handle->_msg_ptr, rr->name, NS_MAXDNAME);
 168         if (b < 0)
 169                 return (-1);
 170         handle->_msg_ptr += b;
 171         if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
 172                 RETERR(EMSGSIZE);
 173         NS_GET16(rr->type, handle->_msg_ptr);
 174         NS_GET16(rr->rr_class, handle->_msg_ptr);
 175         if (section == ns_s_qd) {
 176                 rr->ttl = 0;
 177                 rr->rdlength = 0;
 178                 rr->rdata = NULL;
 179         } else {
 180                 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
 181                         RETERR(EMSGSIZE);
 182                 NS_GET32(rr->ttl, handle->_msg_ptr);
 183                 NS_GET16(rr->rdlength, handle->_msg_ptr);
 184                 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
 185                         RETERR(EMSGSIZE);
 186                 rr->rdata = handle->_msg_ptr;
 187                 handle->_msg_ptr += rr->rdlength;
 188         }
 189         if (++handle->_rrnum > handle->_counts[(int)section])
 190                 setsection(handle, (ns_sect)((int)section + 1));
 191
 192         /* All done. */
 193         return (0);
 194 }
 195
 196 /* Private. */
 197
 198 static void
 199 setsection(ns_msg *msg, ns_sect sect) {
 200         msg->_sect = sect;
 201         if (sect == ns_s_max) {
 202                 msg->_rrnum = -1;
 203                 msg->_msg_ptr = NULL;
 204         } else {
 205                 msg->_rrnum = 0;
 206                 msg->_msg_ptr = msg->_sections[(int)sect];
 207         }
 208 }